The present invention relates to an improved sports shoe.
Sports shoes, such as ski boots, are currently usually produced by injecting plastics at suitable molds in order to obtain a shell and at least one quarter.
For example, French patent no. 2,119,653 discloses a method for manufacturing a ski shoe, comprising a shell and a quarter joined in a single element, which is composed of an outer element and an inner element which are made of two materials and are mutually associated.
The inner element, made of generally rigid plastics, forms at least part of the sole and part of the covering of the ankle and is also open along its front part.
The outer element, made of generally flexible plastics, forms the sole, the front part of the foot, the upper, the heel, a rear part, a covering for the ankle, the foot instep and the part that surrounds the ankle.
This manufacturing method has the drawback that it requires the insertion of the inner element in the outer element.
Furthermore, the inner element has a uniform degree of rigidity in practically all the regions that surround the foot, except for the upper part, so that optimum fit cannot be achieved.
The execution of the inner element by using rigid material furthermore leads to a shoe having a considerable overall weight.
Furthermore, the sole of this shoe which is in contact with the ski is entirely made of rigid plastics, and this further increases the weight of the shoe.
U.S. Pat. No. 3,545,103 discloses a closure device for ski boots comprising a metal side plate that laterally surrounds the outer part of the foot and with which a cuff is rotatably associated.
Although said plate stiffens the boot to a certain extent, it nonetheless does not allow optimum transmission of efforts since it is affected by the tension applied to the lever and affects only the lateral region of the foot.
This allows the leg to move without transmitting the movements to the ski in an optimum manner.
Furthermore, this solution in any case does not allow optimum transmission of efforts from the foot to the ski due to the limited region of the foot affected by the plate.
U.S. Pat. No. 3,067,531 discloses a ski boot composed of a sole to which an inner quarter and an outer quarter are connected; two engagement elements are interposed between said quarters and are arranged longitudinally with respect to them.
The inner and outer quarters are in turn associated, by means of a pivot, to a curved fixed element which is located approximately below the malleolar region, again in the interspace between the two quarters.
This solution, too, has drawbacks, because it does not allow to stabilize the leg, except partially, while skiing; the engagement elements are in fact fixed to the outer quarter at their ends and are thus affected by movements caused by the deformations to which the outer quarter is subjected.
Italian patent no. 1,051,302 discloses a ski boot made of plastics which is essentially constituted by two bodies which mutually overlap along lateral joining lines and are kept in this closed position by fastening means.
The purpose of this solution is to provide a process for manufacturing the boot in a mold without a back draft. The boot comprises parts allowing to adapt it to the devices for fastening it to the ski, as well as a framework formed by thick and rigid ribs and by thin flat portions connecting the ribs.
In any case, even this solution, from the viewpoint of the described technical problem, does not allow to achieve optimum transmission of efforts from the foot to the ski, because the ski is controlled substantially by means of the inner side of the foot, which is not affected by the framework in the illustrated embodiment.
Furthermore, the illustrated embodiment is constituted by multiple elements which must be assembled, thus increasing manufacturing costs.
Furthermore, the arrangement and configuration of the ribs still subjects the boot to slight deformations during sports practice which do not allow optimum transmission of efforts to the ski.
Italian patent application no. 82513 A/87, filed on Feb. 25, 1987 in the name of the same Applicant, discloses a ski boot constituted by a semirigid innerboot with which it is possible to associate at least one first rigid element. The rigid element partially surrounds the lower and lateral regions of the semirigid innerboot. Two second rigid elements are arranged at the sides of the semirigid innerboot and are rotatably associated with the first rigid element and articulated thereto.
This solution was designed specifically for use together with a central binding rigidly coupled to the ski; coupling between the binding and the boot occurred by means of a lateral engagement.
Accordingly, this solution is specific for a particular type of coupling to a ski binding and cannot be transferred directly to a conventional ski boot. This solution is essentially constituted by three rigid elements which must be coupled to each other and to the semirigid innerboot.
This would therefore lead to an increase in manufacturing costs, and the presence of articulations in any case would not allow high-efficiency transmission of efforts for optimum ski control.
French patent no. 2,629,691 discloses a ski boot comprising an articulation, in the form of rivets, located at the front articulation of the foot, and a shell which oscillates at the articulation, where the boot is constituted by a rigid part that affects the tip and the sole of the foot.
A quarter is rotatably associated with the shell and a securing device allows to close the instep together with the heel and the ankle.
The structure also comprises external supports which protrude laterally with respect to the rigid part starting from the regions of the tip and of the heel and converge so as to form an essentially triangular structure, approximately at the upper end of the quarter and thus above the point where said quarter is articulated to the shell.
Devices for adjusting the movement and inclination of the quarter can also be associated at the apex of the triangles.
This solution has some drawbacks: first of all it entails a complicated constructive embodiment for the boot, the purpose whereof is mainly to allow the skier to jump more easily and more naturally while skiing by virtue of the particular articulation of the shell and of the rigid element at the tip.
The shape of the rigid structure thus mainly acts as a guide and articulation for the shell during jumps, whereas the outer supports do not allow optimum transmission of efforts from the foot to the ski, since the heel region is free and the quarter is slideable with respect to said supports.
European patent no. 466,032 discloses the assembly of a boot which combines a flexible shoe, to allow walking, with a frame for the flexible shoe which is associable with the bindings of a ski.
The frame has a single plate, which acts as a sole, interacts with the ski bindings, and has a hollow tip and means for connection to the shoe. Two mutually articulated arms also protrude laterally from the plate, and the upper arm frontally surrounds the tibial region of the shoe.
Even this solution is constructively very complicated and is specifically designed to allow the skier to walk easily once sports activity has ended.
However, the transmission of efforts from the leg to the ski is not ideal because the shoe is not directly connected to the ski bindings and because there are plays in the points for connection to the frame.
International Patent Application No. WO 92/16120 discloses a ski boot comprising a support that can be fixed to the leg above the ankle and is connected to the sole by means of a bar. The support is shaped like a mask that can be fixed to, and cooperates with, at least one part of the shell and is connected to the bar, preferably at a level located between two closed portions of said mask, by means of a bracket that approximately comprises half of the circumference of the leg.
Even this solution is not optimum as regards the transmission of efforts directly to the ski, since it is again constituted by multiple elements coupleable to each other, to the shell, and to the quarter of the boot.
Furthermore, it is noted that the bar is laterally provided with two arms the lower parts whereof are associated at the heel region of the shell.
This solution is not ideal for transmitting efforts to the ski, because this arrangement produces moments that can open out the curve or in the limit produce windmilling.
In connection to the described technical problem, this same Applicant filed an Italian patent application, no. 82601 A/90, disclosing a quarter associated with the shell and having a slot at its lateral regions which has the same or a different inclination, with respect to a guide formed on the shell. A slider is slidingly associated between the slot and the guide.
This solution, too, has drawbacks due to the fact that the quarter is laterally pivoted to the shell by means of studs or by means of a cross-member which can be arranged at a seat formed transversely and below the sole.
On one hand, the quarter in fact has no particular lateral rigidity characteristics due to the material of which it is normally made, and on the other hand the oscillation it can perform does not allow optimum transmission of efforts to the ski, since the function related to varying the inclination obtainable for said quarter is privileged.